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<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
    </head>
    <body>
        <script>
            // 演示 1
            var f1 = function () {
                return a;
            };
            console.log(f1(3));

            var f11 = (a) => a;
            console.log(f11(8));

            // 演示 2
            var f2 = function (a, b) {
                return a + b;
            };
            console.log(f2(3, 4));

            var f22 = (a, b) => a + b;
            console.log(f22(5, 5));
        </script>
    </body>
</html>
